Start with the point
This sounds obvious. It rarely happens early enough.
Before anything else gets planned, the venue, the agenda, the after-dinner activity, get clear on one thing: what do you want people to do differently when they leave? Not what you want them to know, or what slides you want to get through. What behaviour or mindset shift would make this worth the investment?
What is the one thing I want my team to do differently when they leave?
Once you have that answer, everything else flows from it. Sessions, speakers, timings, they either serve that goal or they do not. It is a surprisingly useful filter.